Variable speed drive for a potter{3 s wheel

ABSTRACT

A drive disc is connected to a lower portion of a vertical drive shaft of a potter&#39;&#39;s wheel. An electric motor driven drive cone contacts a flexible peripheral portion of the drive disc. The drive motor is mounted for pivotal movement about a horizontal axis. The drive cone includes a convex drive surface of circular longitudinal curvature which travels a circular curve during motor movement. The motor is moved to change the diameter of the circle of contact of the drive cone with the drive disc, to in that manner change the drive speed of the potter&#39;&#39;s wheel.

United States Patent 1 1 Edwards 1 1 VARIABLE SPEED DRIVE FOR A POTTER 'S WHEEL [76] lnventor: John A. H. Edwards, Box 23 Elandslaagte, Northern Natal, South Africa 22 Filed: Sept. 27, 1973 211 Appl. No.: 401,259

[52] U.S. Cl. 425/459; 74/191; 74/207 [51] Int. Cl. B28b 1/02 [58] Field of Search 425/263, 459; 74/191, 192, 74/193, 207

[56] References Cited UNITED STATES PATENTS 154,156 8/1874 Shuttleworth 74/191 1,193,448 8/1916 Ashton et al. 74/207 1,284,969 11/1918 Anderson 74/194 1,632,795 6/1927 Maimin 74/207 2,459,917 1/1949 Carrington 74/207 [111 3,894,830 14 1 July 15,1975

Smith 74/191 Hankin 425/459 I 57] ABSTRACT A drive disc is connected to a lower portion ofa vertical drive shaft of a potters wheel. An electric motor driven drive cone contacts a flexible peripheral portion of the drive disc. The drive motor is mounted for pivotal movement about a horizontal axis. The drive cone includes a convex drive surface of circular longitudinal curvature which travels a circular curve during motor movement. The motor is moved to change the diameter of the circle of contact of the drive cone with the drive disc, to in that manner change the drive speed of the potters wheel.

2 Claims, 3 Drawing Figures VARIABLE SPEED DRIVE FOR A POTTERS WHEEL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to potters wheels, and more particularly to an improved variable speed drive mechanism for a potters wheel.

2. Description of the Prior Art Prior art drive mechanisms for potters wheels are shown by US. Pat. No. 566,036,granted Aug. 18, 1896 to Daniel Taylor. by U.S. Pat. No. 1,602,122, granted Oct. 5, 1926 to John L. Reed, by U.S. Pat. No. 2.554.836, granted May 29, 1951 to Martin M. Miller. by US. Pat. No. 2,902,741, granted Sept. 8, 1959 to John H. Hanken. Jr., by US. Pat. No. 3.036.355, granted May 29, 1962, to Howard D. Mays et al. by U.S. Pat. No. 3,055,047, granted Sept. 25. 1962. to Carl Preissler. by US. Pat. No. 3.605.218, granted Sept. 20, 1971 to Peter D. Rasmussen and by British Pat. No. 1,223,108, granted Feb. 24. 1971 to .I. W. Ratcliffe and Sons. Ltd. granted Feb. 24, 1971 to .I. W. Ratcliffe and Sons. Ltd.

SUMMARY OF THE INVENTION The variable speed drive mechanism of this invention simply comprises a drive disc which is connected to a lower portion of the potters wheel drive shaft and an electric motor driven drive cone which makes contact with a flexible peripheral portion of the drive disc. The drive motor is mounted to be pivoted in position for the purpose of varying the diameter of contact of the drive cone with the drive disc.

According to an aspect of the invention, the drive motor is mounted onto a base which in turn is mounted for pivotal movement about a horizontal axis. A foot pedal or the like is provided for pivoting the base, and hence the motor driven drive cone supported thereon, about the horizontal axis. Pressure on the pedal pivots the platform in a direction resulting in an increase in the diameter of the ring of contact of the drive cone with the drive disc, and an increase in the drive speed of the potters wheel. The motor is appropriately positioned on the platform so that when pressure is released from the pedal the weight of the motor swings the platform and motor in the speed decreasing direction and into an at rest position in which the drive cone is withdrawn from contact with the drive disc.

The potters wheel is free to be turned by hand when the drive cone is disengaged from the drive disc, i.e. it is free wheeling. Thus, the drive can be disengaged and the wheel used for decorating (e.g. carving or glazing). The wheel is turned by hand as rotation of the product is needed. The motor is allowed to continue running to avoid life shortening starts and stops.

Other features and advantages of the drive mechanism will be apparent from the description of a preferred embodiment of the invention which follows:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a pictorial view of a potters wheel taken from above and looking towards its front and one side, with portions of the exterior housing cut away to show an embodiment of the drive mechanism of this invention;

FIG. 2 is a side elevational view of the potters wheel and its drive mechanism. with the housing omitted; and

FIG. 3 is an enlarged scale fragmentary view of the drive mechanism, including a solid line showing of the drive cone making a small diameter circle of contact with the drive disc and a broken line showing of such drive cone making a large diameter circle of contact with the drive disc.

DESCRIPTION OF THE PREFERRED EMBODIMENT The potters wheel 10 is affixed to the upper end of a vertical shaft 12 which is supported by spaced apart bearings 14. The bearings 14 are mounted on frame portions 16, 18 of a housing or cabinet 20.

According to the invention, the drive mechanism for the potters wheel includes a drive disc 22 which is secured to a lower portion of the vertical shaft 12. Drive disc 22 includes a flexible peripheral edge portion 24. Drive disc 22 may be made from a disc 26 of flexible material which is secured to a rigid backup plate 28. Plate 28 may be substantially identical in form to the potters wheel 10.

The drive mechanism also includes a drive cone 30 which is rotated by an electric motor 32. The motor 32 is mounted onto a platform 34 which is mounted for pivotal movement about a horizontal axis 36. A foot pedal 38 or the like might be provided for pivoting the platform 34. Cone 30 includes a convex drive surface which in the axial or longitudinal direction is of circular curvature.

According to an aspect of the invention, the center of curvature of the drive surface of the drive cone 30 coincides with the pivotal axis 36. Thus, pivotal movement of platform 34 moves the drive surface along a circular curve (FIG. 3). The flexible periphery 24 is deflected some when it is in contact with the drive cone 30. the material used is stiff enough so that when it is deflected it is self biased into contact with the drive cone 30. The force of contact of the drive surface with the flexible periphery 24 does not change but the diameter of the circle of contact of drive cone 30 with the flexible periphery 24 does change. As a consequence, the drive speed of the drive disc 22, and hence the potters wheel 10, also changes.

As best shown by FIG. 3, the drive disc member 26 may be beveled at 40 where it makes contact with the curved surface of the drive cone 30. Also, the point end of the drive cone 30 is rounded so that it can cam the flexible portion 24 into a deflected position without cutting into the material used for part 24.

According to another aspect of the invention, the motor 32 is mounted to be offset from the pivotal axis 36 on the side thereof opposite the drive disc 22. This is done so that the weight of the motor 32 will serve to rotate the platform 34 into an at rest position in which the small diameter end of the drive cone 32 is contiguous the drive disc 22. When the drive motor 32 is at rest the drive cone may be removed from actual contact with the drive disc 22, i.e. the drive mechanism may be in a neutral or a non-drive position.

Referring to FIGS. 1 and 2, the cabinet frame may comprise a pair of parallel frame members 44, 46 between which a shaft 48 extends. The motor support platform 34 may include a pair of depending arms 50 to which the shaft 48 is secured. Shaft 48 may include end portions which project outwardly beyond members 50 and through openings in the frame members 44, 46,. Shaft 48 may be rotatable relative to the frame members 44, 46 and the members 50, 34 may be fixed relative to the shaft 48 so that they move with it. A pedal support arm 52 may extend outwardly from one of the members 50 and support a foot pedal operated lever 38 at its outer end The cabinet encloses the drive mechanism 22, 30, 32. etc. and hence protects it against most of the drippings from the product on the potters wheel 10. However, one advantage of the drive mechanism of this invention is that it can receive dripping off from the product on the potters wheel 10 and still function properly. Another advantage of the potters wheel drive of this invention is that the potter can control the speed of rotation of the potters wheel both at the potters wheel and at the drive mechanism. The potter places his hands on the clay product which is being turned by the wheel l0. The pressure exerted by the potter on the product constitutes an increase in load and tends to slow down the wheel 10. The drive mechanism is not harmed by this increase in load because the drive is a frictional drive. lf the pressure applied by the hands exceeds a predetermined value, slippage will occur between the drive cone and the drive disc 40. If the resulting slow down is objectionable the potter can easily and quickly increase the potters wheel speed to the desired level by an adjustment in position of the drive cone 30, so as to increase the diameter at the ring of contact of the drive cone 30 with the drive disc 24.

Although the invention has been described in a preferred form with a certain degree of particularity, it is to be understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination arrangement parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

l. in a potters wheel having a generally vertical drive shaft, a rotatable turn table at the upper end of said drive shaft, bearing means supporting the shaft for rotation, an improved variable speed friction drive mechanism comprising:

a drive disc connected to the shaft below said turn table, an electric motor including an output shaft, a drive cone secured to said output shaft, said drive cone having a base portion of a relatively large diameter and reducing in diameter from said base outwardly to a tip at a rate resulting in the drive surface of the drive cone being of circular curvature axially of the drive cone, with the drive surface of the drive cone being contactable with a lower peripheral portion of the drive disc, means mounting said motor for pivotal movement about a horizontal axis which extends transversely of the output shaft axis, said axis being located radially outwardly from the axis of rotation of the vertical drive shaft and below the drive disc, between the drive motor and the drive disc, and substantially at the center of axial curvature of the drive cone, so that the weight of the drive motor tends to rotate the drive cone in a direction placing the tip of said drive cone contiguous the periphery of the drive disc, and control lever means for pivoting the motor about said generally horizontal axis, for moving the drive cone axially, so as to change the diameter of a circle of contact of the drive cone with the drive disc, to in that manner change the drive speed of the drive disc by the drive cone, and wherein the drive cone is made from a relatively hard material and the drive disc comprises a flexible peripheral portion which is deflected some when it is in contact with the drive cone, said flexible peripheral portion having sufficient stiffness so that when deflected it is self-biased into friction contact with the drive cone.

2. A potters wheel according to claim 1, wherein said drive disc comprises a first rigid disc of a first diameter and a coaxial and contiguous flexible second disc of a larger diameter, and wherein the portion of the second disc which is disposed radially outwardly of the first disc constitutes the flexible peripheral portion of said drive disc. 

1. In a potter''s wheel having a generally vertical drive shaft, a rotatable turn table at the upper end of said drive shaft, bearing means supporting the shaft for rotation, an improved variable speed friction drive mechanism comprising: a drive disc connected to the shaft below said turn table, an electric motor including an output shaft, a drive cone secured to said output shaft, said drive cone having a base portion of a relatively large diameter and reducing in diameter from said base outwardly to a tip at a rate resulting in the drive surface of the drive cone being of circular curvature axially of the drive cone, with the drive surface of the drive cone being contactable with a lower peripheral portion of the drive disc, means mounting said motor for pivotal movement about a horizontal axis which extends transversely of the output shaft axis, said axis being located radially outwardly from the axis of rotation of the vertical drive shaft and below the drive disc, between the drive motor and the drive disc, and substantially at the center of axial curvature of the drive cone, so that the weight of the drive motor tends to rotate the drive cone in a direction placing the tip of said drive cone contiguous the periphery of the drive disc, and control lever means for pivoting the motor about said generally horizontal axis, for moving the drive cone axially, so as to change the diameter of a circle of contact of the drive cone with the drive disc, to in that manner change the drive speed of the drive disc by the drive cone, and wherein the drive cone is made from a relatively hard material and the drive disc comprises a flexible peripheral portion which is deflected some when it is in contact with the drive cone, said flexible peripheral portion having sufficient stiffness so that when deflected it is self-biased into friction contact with the drive cone.
 2. A potter''s wheel according to claim 1, wherein said drive disc comprises a first rigid disc of a first diameter and a coaxial and contiguous flexible second disc of a larger diameter, and wherein the portion of the second disc which is disposed radially outwardly of the first disc constitutes the flexible peripheral portion of said drive dIsc. 